1. Field of the Invention
This invention relates to polymeric hydrogels, and, more particularly, to a polymeric hydrogel product of a non-continuous, vinyl lactam polymeric composition having two phases therein, obtained by irradiating the composition with high energy electron beam or gamma-radiation.
2. Description of the Prior Art
Polymeric compositions of vinyl lactam monomers generally are one-phase, soluble, high viscosity materials. These compositions are found in a variety of commercial applications such as film formers, dye transfer inhibitors, rheology modifiers, dispersants, excipients, and drug delivery. Aqueous gels of these monomers can also be prepared by light covalent or associative crosslinking of polymer chains resulting in a highly swellable, one-phase material of high viscosity.
The prior art for these compositions are represented by the following patents.
Niessner, in U.S. Pat. Nos. 5,149,750 and 5,180,804, disclosed finely divided, water-swellable gel-like, water-swellable copolymers by polymerization of comonomers in the presence of a surfactant.
Liu, in U.S. Pat. No. 5,997,855, described a homogeneous terpolymer for hair care use, however, without a crosslinking agent.
Kopolow, in U.S. Pat. No. 5,130,121, described personal care compositions containing a stabilized cosmetically-active product obtained by in situ polymerization of a water-soluble vinyl monomer in the presence of discrete microdroplets of a cosmetically-active oil in water.
Blankenburg, in U.S. Pat. Nos. 5,635,169 and 6,107,397, also described uncrosslinked aqueous copolymer dispersions of nonionic water-soluble monomers with N-vinyl groups, and hydrophobic monomers.
Steckler, in U.S. Pat. No. 3,878,175, disclosed highly absorbent spongy gel polymer materials by simultaneously copolymerizing and partially crosslinking a comonomer mixture of an alkyl acrylate and a heterocyclic N-vinyl monomer containing a carbonyl functionality in the presence of a hydrophobic liquid diluent in which the final polymer is insoluble.
Markus, in U.S. Pat. No. 2,810,716, described a process for making swellable resins by copolymerizing monomers in the presence of a water-soluble non-redox divalent-ion containing salt.
Tseng, in U.S. Pat. Nos. 5,393,854 and 5,717,045, disclosed a one-phase, aqueous gel of crosslinked copolymers of vinyl pyrrolidone and dimethylaminoethyl methacrylate for use in hair care products. The crosslinking agent was 1-vinyl-3-(E)-ethylidene pyrrolidone. The gels had a Brookfield viscosity of between 60,000 and 100,000.
These references illustrate the desire of the art to produce a continuous network of polymer molecules, or microgel, in a one-phase system, and of high viscosity.
However, none of these references show, describe or suggest a two-phase polymeric hydrogel product.
Accordingly, it is an object of the present invention to provide a polymeric hydrogel product of an aqueous polymeric composition which is a combination of a film-forming polymer and substantially uniformly dispersed, minute resinous particles that, under suitable light magnification, shows the presence of two discrete phases therein, one of which is a water-soluble polymer, and the other is in situ-formed, water-insoluble resinous particles.
Another object of the invention is to provide such a polymeric hydrogel product for use in making inkjet printing films as described in detail in the aforementioned copending patent applications.
A feature of the invention is the provision of a polymeric hydrogel formed by irradiating a two-phase polymeric composition with high energy electron beam or gamma-radiation.